The present invention is particularly applicable for use in mounting a standard electromechanical relay onto the door or wall of a cabinet used to house electrical equipment, including relays, and it will be described with particular reference thereto; however, it is appreciated that the invention has broader applications and may be used to mount standard electromechanical relays onto various panels.
In controlling industrial equipment, it is common practice to employ a large number of electromechanical relays which are generally packaged to have substantially uniform outer dimensions. At least, a line of relays of a particular manufacturer will have relative standardized outer dimensions. Such relays have internal coils, a base with prongs to plug into an electrical circuit and internal magnetically actuated components to shift the electrical condition between the various connector prongs at the base of the relay. These electromechanical relays are generally mounted on a rack or support structure located within a cabinet having an access door. Since a large number of these relays are closely positioned within the cabinet or enclosure, access to the relays is not always convenient. This assembly arrangement for relays is widely used and is quite acceptable, except when certain relays have visual indicators or manipulative components on the relay itself. For instance, it is quite common to provide relays with a rheostat which is adjustable at the outer surface or face of the relay. In addition, some relays have lights to indicate whether or not the relay is energized. Other relays have a counting feature which includes digit setting units on the relay itself. Other relays have latching pins, such as shown in U.S. Pat. No. 4,097,832. As can be seen from this general summary, electromechanical relays are becoming more complex and include components manually adjustable at the relay itself so that circuit characteristics can be modified without changing components or without adding additional components to the previously assembled circuitry. Using relays of the type having a visual or manipulative component on a face thereof, the maintenance or engineering personnel had to gain access to the cabinet or enclosure for making observations with respect to certain relay conditions and for changing the electrical characteristics or parameters of the various relays. These cabinets are often located in close quarters and in environments which are not optimum for relays and other electrical components within the enclosure or cabinet. Thus, the tediousness and inconvenience of making observations and adjustments at the various relays within a cabinet has been a hindrance to using the more complex relays. This is even more disadvantageous when only a limited number of relays need attention. To overcome this difficulty, some companies have tapped into the various relays and wired the control devices onto the door of the cabinet or enclosure. In some instances, a rheostat is fixed to the door and leads are directed from the rheostat to a particular relay mounted within the cabinet so that the rheostat for controlling functions of the relay is removed from the relay itself and placed on the door or cabinet wall. This modification of the existing relay is expensive. It involves modification of a relay. The long leads often require shielding and have resulted in certain noise interference. By bringing the rheostat to the door for external manipulation, a standard available relay with an internal rheostat is not used. The same remote connection concept has been employed for wiring indicator lights on the door and connecting the lights to the internal circuitry. Although rheostats and indicator lights can be wired remotely for controlling the circuitry involving certain relays, this arrangement for changing the condition of the various relays is not acceptable for certain functions. For instance, a mechanical latch which is available on some relays could not be remotely connected in this fashion. In addition, thumb wheels of digital circuits require a great number of wires which must be directed from the relay to the remote location on the door of the cabinet if external manipulation is to be provided without opening the cabinet or enclosure. In summary, certain relays, which are to be provided with visual or manipulative components, can be assembled at the job site by external wiring. Such external wiring cannot be used universally for various relays having such visual and manipulative features. For that reason, such external wiring still does not negate the necessity for setting certain relays which are in the cabinet and cannot use complicated remote wiring. It is, therefore, still the general practice to use relays specifically provided with visual and manipulative features on the face thereof within the cabinet itself and which can be observed and adjusted only by obtaining access to the interior of the enclosure or cabinet.